Pressing tools particularly for the manufacture of large-area pressings



Dec. 15, 1959 K. LANG ETAL 2,916,771

PRESSING TOOLS PARTICULARLY FOR THE MANUFACTURE OF LARGE-AREA PRESSINGS3 Sheets-Sheet 1 Filed NOV. 16, 1955 3 Sheets-Sheet 2 LANG ET ALPRESSING TOOLS PARTICULARLY FOR THE MANUFACTURE OF LARGE-AREA PRESSINGSDec. 15, 1959 Filed Nov. 16, 1955 United States PatentO lice PRESSINGTOOLS PARTICULARLY FOR THE MAN UFACTURE OF LARGE-AREA PRESSINGS KurtLang, Wolfgang Barthel, Wilhelm Ladewig, Fritz Hans, and WernerReichelt, Zwickau, Erich Klauss, Mose], near Zwickau, and AlfredSchiidlich, Zwickau, Germany The present invention relates to pressmolding machines, and more particularly to pressing tools forming partthereof which are capable of being heated and cooled for the manufactureof predominantly large-area pressings consisting preferably of syntheticmaterials.

It is known in the art to provide thick-walled steel tools for thepressing of large-area pressings. In these tools pressures of250-400kilograms per square centimeter are applied, the material flowingonly at such high pressures. However, thick-walled tools cannot beapplied to pressings which are to be cooled after the pressing operationbecause the required cooling after each pressing takes too much time andthus is uneconomical.

It is an object of the present invention to provide a pressing tooladapted to press large-area parts to be cooled after the pressingoperation.

It is another object of the present invention to equalize anydifferences, in the accumulation of the material in the body to bepressed. I

According to one embodiment of the present invention large-areapressings to be cooled after the pressing operation are manufactured bymeans of pressing tools in which a heat insulating layer is arranged onthe base memberiof the lower portion of the tool, andfa shellshaped moldprovided with'heating channels is arranged on the heat insulating layerwhereas the upper part of the tool is provided with a rubber padtraversed prefer- 2,916,771 -Pa t ented Dec. 15, 1959 2, v a part of apressing tool according to the present invention, r t

Fig. 7 is asectional part elevation on an enlarged scale of anotherembodiment of the present invention,

Fig. 8 is a sectional elevation of a further embodimentv of the presentinvention,

Fig. 9 is a sectionalelevation on an enlarged scale of part of theembodiment shown in Fig. 8,

Fig. 10 is a part section of still another embodiment of'the presentinvention,

Fig. 11 is a sectional elevation of a still further embodiment of thepresent invention,

Fig. '12 is a sectional elevation on an enlarged scale along the line ABshown in Fig. 13, t

Fig. 13 is a plan view of some parts shown in Fig. 12, and

Fig. 14 is a sectional elevation of part of a pressing toolincorporating the parts shown in Figs. 12 and 13.

Referring now to the drawings in detail and first to Fig. .1, a basemember 3 is provided with a bowl shaped recess 1. An insulating layer 6consisting of a material being a poor conductor of heat is arranged inthe recess 1, the layer 6 being-rigidly connected to the base member 3by suitable means 7. The heat insulating layer 6 is subdivided byseparating fillets or bars 10 into square panels having dimensions ofabout 200 millimeters X 200 ably by heating tubes and being attached tothe countermember or press ram by means of an interposed heat insulatinglayer.

The rubber pad is intended to equalize any diflierences in theaccumulation of materials of'the preliminary body to be pressed, and anychanges of the pressing 'gap caused by heat expansion ofithe material.Without this rubber pad it is impossible to press the preliminarymaterial'in a perfectly uniform manner at low pressures amountingapproximately to 40 kilograms per square centimeter. This holdsparticularly for parts to be subjected to a high degree of deformation.

The baseymember for the lower portion of the tool as well as fortherubber pad consists perferably of cast iron, compact timber,steel'with magnesite, the material known under the trade name Igurit,concrete, or similar materials.

Other objects and advantages of the present invention will becomeapparent from the following detailed description thereof in connectionwith the accompanying drawings showing, byway offexample, someembodiments of a pressing tool according to the present invention. Inthe drawings p p Fig. 1 is a sectional elevation of part of a pressingtool for parts capable of an easy deformation,

Figs. 24 illustrate several embodiments of fastening means for a rubberpad forming part of the pressing tool shown in Fig. 1, e p t Fig. 5 is asectional elevation onan enlarged scale of part of the pressing moldshown in Fig. 1,

Fig. 6 is a sectional elevation of a swage for making millimeters. Athin foil 19 consisting preferably of rolled lead is arranged on theinsulating layer 6. 'A 'shellshaped mold 14 preferably consisting ofneatly machined steel is provided on the lower side thereof with aplurality of heating channels 2. t

As shown in Fig. 5, the heating channels 2 are covered bytcover sheets4co nsisting preferably of metal which are separated from each other byfilling strips or hands 5 in order to obtain a smooth contact andsliding surface. Themetal sheets 4 and filling strips.5 are welded bywelding joints 5:; to the shell-shaped mold 14, the upper side ofwhich-corresponds to the shape of the article (not shown) to be pressedfrom a synthetic material by the pressing tool. I V p The prepressedmaterial (not shown) is pressed into the shell-shaped mold 14 by means-of a rubber pad 11 consis'ting of a synthetic rubber of mediumhardness, or a similar-heat resistant rubber mixture. The rubber pad 11is surrounded by'a strong frame 12 "and vulcanized with the rim portionthereof to the latter. However, if desiredthe rubber pad 11may'befastened to the frame 12 by screw bolts 16 cooperatingwithcountermembers 17 such as nuts and sleeves 18 arranged on the screw"bolts 16 between the frame 12 and the countermember 17. This kind ofconnection facilitates and accelerates the exchange of the rubber pad11.

A system of heating pipes 13is arranged in the rubber pad 11 near the"upper side thereof. An insulating layer 9 consisting of a material beinga poor conductor of heat is arranged above therubber pad 11. Acountermember or pressing ram 8 is arranged above the insulating'layer'9 which is subdivided by Z-shaped brackets 15 fastened by screw boltssuch as 1511 to the pressing ram 8. I The 'Z-shaped parts 15 extendthrough the insulating layer 9 and form the cover of the recesses 13aprovided in the rubber pad 11 accommodating the heating pipes 13.TheZ-shaped parts 15 carry the rubber pad 11 by means of parts such asstirrups 33 and anchoring members 32 vulcanized into the rubber pad 11.The insulating layer 9 is subdivided into small fields by partitions 10similar to the insulating fillets or bars 10 arranged in the heatinsulating layer 6. The" mold 14 is connected with the rim thereof by aconnectingmember 20a arranged at the rim portion of the heat insulatinglayer 6, to a centering 3 member connected'to' the base member 3 byscrews such as 20b.

The operation of this device is as follows:

If an article is to be pressed by the pressing tool describedher'einabove the pr'e'ssingram 8, the" insulating layer 9 and the rubberpad 11 are lifted from the'position shown in} Fig. 1 by drivingmeans(not shown). A heating fluid such as steam is admitted to the heatingchannels 2 and pipes 13 so as to heat thoroughly the shell-shaped mold14 and the rubber pad 11; After the same are sufficiently heated, thematerial to be pressed, preferably a synthetic materiahis insertedbetween the shell-shaped mold 14 and the rubber pad' 11. Then themovable parts of thepressing tool including the pressing ram 8,theinsulating layer 9, and the rubber pad 11 are lowered so thatthe'material to-be' pressed is caught between the shell-shaped mold 14and the rubber pad 11, the'deformation' of the material being promotedand facilitated by the heattransferred to the mold 14 and the pad 11 bythe heating fluid circulating in the channels 2 and the pipes 13;After'thematerial to be pressed, preferably a synthetic-material hasbeen shaped, the heating. fluid circulatingiin'the channels 2 and thepipes 13 is replaced by a cooling agent which circulates through thechannels 2 and the pipes 13 so that the pressed article is rapidlycooled andniay be removed from the pressing tool after lifting themovable parts 8, 9, and 11' thereof. The pressed part is then removedand the pressing tool is ready for a further operation.

The shell-shaped mold 14 consists preferably of steel and is so thin,for instance 12-18 millimeters thick, that it may be manufactured from aflat steel plate which in the fiat condition thereof is machined andfinished and provided with the heating channels 2. After performingthese steps the plate is pressed in warm condition in a swage shown incross-section in Fig. 6 andconsisting of a-lowerpart 63 and an upperpart 64. In many cases the base member 3 shown in Fig. 1 may be formedso as to be usable as part of a swage for imparting to the mold'14 thefinal shape thereof.

The foil 19 consisting preferably of rolled lead facilitates anydisplacements of the mold 14-against the heat insulating layer 6.

Referring now to the modified embodiment shown in Fig. 7, a shell-shapedmold-714 is attached on the lower side thereof by a welding joint 70 toa relatively short threaded sleeve 71 into which the end 72 ofaholdingscrew 30 projectsthrough the base member 73 and the heat insulatinglayer 76. v

Referring now to Figs. 8 and 9 of the drawings showing' a mold formanufacturing highly deformed molded pieces, the mold' 814 is shaped asa part manufactured from a steel plate having a uniform thickness t. Themold 814'is' secured to an auxiliary'member 831 having a smooth andcontinuously curved lower side 809 enabling the auxiliary member 831' toyield to, and if desired, to slide on, the supporting or base member(not shown) under the influence of heat, particularly during the heatingup stage. If the auxiliary member 831 consists of heat insulatingmaterial the heat insulating layer 6 shown in Fig. 1 may be omitted. Theheat insulating member 831 is preferably subdivided 1nto square fieldsbyfillets or bars 810. Onthe lower side of the mold- 814' are providedheating channels 811 which are limited by chutes 821 welded by weldingmaterial such as 812 to the lower side of the smooth mold 814.Ifd'esired, the mold 814 may be held inposition by screws such' as 816arranged in a boring of the auxiliary member 831 and engaging acountermember as nuts 815 provided on the lower side of the mold 8Referring now to Fig. 10 of the drawings the mold 1014' is' formed as acast piece provided with heating channels 1002' arranged in the" mold'1014.

Referring now to Fig. 11 of the'drawings a pressing tool is shown forpressing parts having unilaterally raised left and right hand edges. Thebase member 1103 is provided in the center thereof with an expansionjoint 1124. The left part 1114 and the right part 1114a of the mold areprovided, respectively, with portions 1116 and 1116a having a reducedthickness and being connected by a holding ledge 1123 secured inposition by meansof a screw bolt 1125 extending through the expansionjoint 1124. A metal sheet 1122 covers the holding ledge 1123, the sheet1122 joining to each other the parts lil l'and 1114a of the mold 1114. Aheat insulating layer 1106 is subdivided by separating fillets or bars1110 into square panels-similar to those shown in the embodiment shownin Fig. 1.

Referring now' to Pig's. 12-14 of the drawings, a mold is shown intendedfor the manufacture of large-dimen sionedmoldedpieceshaving uprightedges which either extend overthe wholecircumference of the molded pieceor are provided-on two'opposite parts thereof; As shown in Figs. 12 and14 the mold consists of two parts 1214 and 1214a'similar to those shownin Fig. 11. The expansion joint 1224 arranged between the'two halves1214 and 1214a of the mold is covered by a metal strip 1229 welded toone of the halves, for instance 1214 by a welding seam1230. Between thefree edge of the metal strip 1229 and the other half, say 1214a,-of themold a groove 1226 is formed which has a width changeable according tothe heat expansion of the metal strip 1229, the synthetic material (notshown) during the pressing step filling the groove 1226. On the lowerside of the halves 1214 and 1214a of the mold are provided fingers 1227,1228 covering the lower end of the expansion joint 1224 and welded,respectively, by welding joints or seams 1225, 1232 to the parts ofthemold. As will be seen from Fig. 13 the fingers 1227, 1228 are weldedalternately to the parts 1214 and 121%; of the mold, the finger 1228beingwelded by the welding seam 1232 to the part 1214, The part 1214 ofthe mold is separated by a gap 1234 from a centering member 1204 held byscrews 1205 on the base member 1203 and holding the insulating layer1206 in position, the insulating layer 1206 supporting the part 1214 ofthe mold. The. right part 1214a is provided with a-cen'tering member1236 held in position on the base'member 1203 by a screw 1238'.

Although the present invention has been described hereinabove withreference to the embodiments of a pressing tool shown in" the drawingsit'should'be understood that the present invention" is' in no waylimited to the embodiments shown in the'drawings and that variousmodifications thereof, changes, and substitutions of equivalents will beapparent to" those skilled in the art, the embodiments of a pressingtool described'-hereinabove being only to be understood as examples ofthe present invention.

We claim:

1. A'molding tool adapted topress-mold synthetic material of relativelylarge area comprising, a rigid base; a heat insulating layer anchored tosaid base; and a mold liner of relatively hard, heat conducting materialnested on said insulating layer, said insulating layer being Iinterposedbetween said base and said liner andthereby substantially insulates theformer from the latter, said liner having an exposed surface adapted toreceive material to be'molded and also having at least one channel forcarrying fluid for varying the temperature of said liner, said linerbeing slidable supported and loosely arranged on said insulating layerfor relative displacement therebetween to accommodate relative thermalexpansion and contraction, and a rolled lead foil interposed betweensaid insulating layer and said liner to facilitate relative displacementbetween said liner and said insulating layer.

2. A moldingtool adapted to press-mold synthetic material ofrelativelylarge area comprising, a'rigid base; a

heat insulating layer anchored to said base; and a mold liner ofrelatively hard, heat conducting material nested on said insulatinglayer, said insulating layer being interposed between said base and saidliner and thereby substantially insulates the former from the latter,said liner having an exposed surface adapted to receive material to bemolded and also having at least one channel for carrying fluid forvarying the temperature of said liner, said liner being slidablesupported and loosely arranged on said insulating layer for relativedisplacement therebetween to accommodate relative thermal expansion andcontraction, the rim of said liner is slidingly supported with respectto said heat insulating layer.

3. A molding tool adapted to press-mold synthetic material of relativelylarge area comprising, a rigid base; a heat insulating layer anchored tosaid base; and a mold liner of relatively hard, heat conducting materialnested on said insulating layer, said insulating layer being interposedbetween said base and said liner and thereby substantially insulates theformer from the latter, said liner having an exposed surface adapted toreceive material to be molded and also having at least one channel forcarrying fluid for varying the temperature of said liner, said linerbeing slidable supported and loosely arranged on said insulating layerfor relative displacement therebetween to accommodate relative thermalexpansion and contraction, said liner has a plurality of .channels opentowards said insulating layer, further comprising, cover sheet meansarranged on the open sides of said channels, and filler strips arrangedbetween said cover sheet means, said filler strips and said cover sheetmeans forming a smooth contact surface slidingly engaging saidinsulating layer.

4. A molding tool as claimed in claim 2 further comprising, stopssecured to said base member, said stops being positioned to limit therelative displacement between said liner and said insulating layer.

5. A molding tool adapted to press-mold synthetic material of relativelylarge area comprising, a rigid base; a heat insulating layer anchored tosaid base; and a mold liner of relatively hard, heat conducting materialnested on said insulating layer, said insulating layer being interposedbetween said base and said liner and thereby substantially insulates theformer from the latter, said liner having an exposed surface adapted toreceive material to be molded and also having at least one channel forcarrying fluid for varying, the temperature of said liner, said linerbeing slidable supported and loosely arranged on said insulating layerfor relative displacement therebetween to accommodate relative thermalexpansion and contraction, said liner comprises to two adjacent sectionsdefining an expansion joint therebetween.

6. A molding tool as claimed in claim 5, and a metal strip welded to therim of one of said first and second liner sections and extending tooverlap the expansion joint between said first and second linersections.

7. A molding tool as claimed in claim 5, and fingershaped memberssecuring the edges of said first and second liner sections in positionalong the expansion joint.

8. A molding tool as claimed in claim 7, said fingershaped members beingsecured alternately to the lower sides of said first and second linersections so as to engage the edges thereof along the expansion joint.

9. A molding tool adapted to press-mold synthetic material of relativelylarge area comprising, a rigid base, a heat insulating layer anchored tosaid base, and a mold liner of relatively hard, heat conducting materialnested on said insulating layer, said insulating layer being interposedbetween said base and said liner and thereby substantially insulates theformer from the latter, said liner having an exposed surface adapted toreceive material to be molded and also having at least one channel forcarrying fluid for varying the temperature of said liner, said linerbeing slidable supported and loosely arranged on said insulating layerfor relative displacement therebetween to accommodate relative thermalexpansion and contraction, a countermember, a heat insulating layeranchored to said countermember, and a die member of elastic material,said material being uniformly solid throughout its body, said die memberbeing vulcanized to said last-mentioned insulating layer and having adeformable surface turned toward the exposed surface of said liner, saidlast-mentioned insulating layer being interposed between saidcountermember and said die member, said deformable surface being urgedinto contact with the material to be molded upon said countermember andbase member being forced together under pressure, and said die memberbeing provided with channels for carrying a fluid for changing thetemperature of said die member, and a frame enclosing said die member,screw means supported in said frame, nut means arranged for cooperationwith said screw means, said nut means consisting of a vulcanizablematerial embedded in said die member and hollow distance pieces arrangedbetween said frame and said nut means, said screw means extendingthrough said hollow distance pieces.

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